Forgiving is an important capability. It does more for the forgiver than for the forgiven. But it should not be a universal, indiscriminate behaviour. It is legitimate not to forgive sometimes. It depends, of course, on the severity or duration of what was done to you.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 2 DVDs with 12 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)